This invention relates to improvements in a magnetic recording medium, and more specifically to improvements in a back coating to be formed on the back of the base for the magnetic recording medium.
The magnetic recording medium is in extensive use in audio and video recording and also in computer and other fields. Especially, video tape cassettes (e.g., of the VHS and beta systems) have enjoyed widespread use in recent years. Consequently, intensive and earnest studies are being carried on to realize commercial production of video cassette tapes capable of recording and playing for long periods of time, in the same manner as thin audio cassette tapes have succesfully been merchandised for extended recording and playing time.
For the tape performance the characteristics of the magnetic recording layer formed on one side of a tape base is, of course, a chief determinant. Also, it is to be noted that the characteristics of the back surface of the base are important considerations in use of the tape and from the standpoint of overall tape characteristics. Because of the trend towards adoption of ever thinner tape bases, forming a thin coating on the back of the tape for the reinforcement purpose has been proposed. However, among others the following matters become a problem:
1. Video S/N PA1 2. Cinching (loosening of tape roll on quick stop) PA1 3. Wear of back coating PA1 4. Mutual adhesion of magnetic layer and back coatings on adjacent layers of wound tape
The back coating is required to have these characteristics in a balanced way. Heretofore, adequate consideration has seldom been given to the characteristics in general, and no magnetic recording tape has been introduced yet which has a back coating with well-balanced characteristics.